Process and a device for the rotation-angle-monitored tightening or loosening of screw connections

Abstract

The invention relates to a process and a device for the rotation-angle-monitored tightening or loosening of screw connections by means of power driven tools. The absolute rotation angle swept over in the screwing operation with respect to a fixed point about a swivel axis through the rotation axis of the screw connection is measured. An advantageous, relative-position free, absolute measurement of the rotation angle is effected by the use of an absolute rotation-rate measuring sensor. The rotation-rate sensor can herein be configured as a mechanical, compass-like gyroscope, as a rotation sensor or as an acceleration sensor, by means of which a measured value correlated with the absolute rotation angle can be recorded.

What is claimed is: 
     
       1. Process for rotatably driving a threaded fastener using a tool of the type having a housing and a rotatable fastener drive part carried by the housing, said process comprising: determining a first angle corresponding to the rotation angle of the drive part with respect to the housing,   determining a second angle corresponding to the rotation angle of the housing with respect to a fixed point, and   determining an absolute rotation angle of the drive part with respect to the fixed point by combining the first and second angles.   
     
     
       2. Process according to claim 1, wherein said tool is a power driven tool with a hand held housing, and further comprising determining when a predetermined tool tightening torque has been reached during tightening of a threaded fastener connection with said tool. 
     
     
       3. Process according to claim 2, wherein said determining of said first and second angles is commenced after said determining of the predetermined tool tightening torque. 
     
     
       4. Process according to claim 3, further comprising controlling the operation of the tool as a function of the determined absolute rotation angle. 
     
     
       5. Process according to claim 2, further comprising controlling the operation of the tool as a function of the determined absolute rotation angle. 
     
     
       6. Process according to claim 3, wherein said combining of the first and second angles is done using an electronic unit carried by the housing. 
     
     
       7. Process according to claim 1, wherein said fixed point is located on an axis which is parallel to the drive part rotational axis. 
     
     
       8. Process according to claim 7, wherein said fixed point is located on the drive part rotational axis. 
     
     
       9. Process according to claim 1, wherein said determining said second angle includes directly sensing the rotative position of the housing. 
     
     
       10. Process according to claim 9, wherein said determining said second angle includes using a gyroscope to generate a second angle signal. 
     
     
       11. Process according to claim 1, wherein said determining said second angle includes sensing the rotation velocity of the rotation of the housing and then integrating and correlating the rotation angle with the determined first angle to determine said absolute rotation angle. 
     
     
       12. Process according to claim 11, wherein said sensing the rotation velocity includes using an optical gyroscope. 
     
     
       13. Process according to claim 1, wherein said determining of said second angle includes sensing the angular acceleration of the housing and then doubly integrating and correlating the sensed rotation angle with the determined first angle to determine said absolute rotation angle. 
     
     
       14. Tool apparatus for rotatably driving a threaded fastener including a tool of the type having a housing and a rotatable fastener drive part carried by the housing, said tool apparatus comprising: a first angle determining device for determining a first angle corresponding to the rotation angle of the drive part with respect to the housing,   a second angle determining device for determining a second angle corresponding to the rotation angle of the housing with respect to a fixed point, and   an absolute rotation angle determining device for determining an absolute rotation angle of the drive part with respect to the fixed point by combining the first and second angles.   
     
     
       15. Tool apparatus according to claim 14, wherein said tool is a power driven tool with a hand held housing, and further comprising a torque determining device for determining when a predetermined tool tightening torque has been reached during tightening of a threaded fastener connection with said tool. 
     
     
       16. Tool apparatus according to claim 15, wherein said devices are operable such that said determining of said first and second angles is commenced after said determining of the predetermined tool tightening torque. 
     
     
       17. Tool apparatus according to claim 16, further comprising tool control apparatus for controlling the operation of the tool as a function of the determined absolute rotation angle. 
     
     
       18. Tool apparatus according to claim 16, wherein an electronic unit carried by the housing is used to combine the first and second angles. 
     
     
       19. Tool apparatus according to claim 15, wherein said hand held housing rotates radially from the drive part rotational axis. 
     
     
       20. Tool apparatus according to claim 14, further comprising tool control apparatus for controlling the operation of the tool as a function of the determined absolute rotation angle. 
     
     
       21. Tool apparatus according to claim 20, wherein said second angle determining device includes a gyroscope. 
     
     
       22. Tool apparatus according to claim 21, wherein said gyroscope is a mechanical gyroscope. 
     
     
       23. Tool apparatus according to claim 20, wherein an electronic data processing device is provided for combining the first and second angles, said data processing device being carried on the housing. 
     
     
       24. Tool apparatus according to claim 23, wherein said data processing device includes apparatus for initiating tool control signals as a function of torque applied to the fastener drive part and of the absolute rotation angle. 
     
     
       25. Tool apparatus according to claim 24, wherein said data processing device includes a subtraction unit for linking the second angle with a drive part torsion angle present at a known torque. 
     
     
       26. Tool apparatus according to claim 14, wherein said fixed point is located on an axis which is parallel to the drive part rotational axis. 
     
     
       27. Tool apparatus according to claim 26, wherein said fixed point is located on the drive part rotational axis. 
     
     
       28. Tool apparatus according to claim 14, wherein said second angle determining device includes apparatus directly sensing the rotative position of the housing. 
     
     
       29. Tool apparatus according to claim 28, wherein said second angle determining device includes a gyroscope. 
     
     
       30. Tool apparatus according to claim 14, wherein said second angle determining device includes apparatus sensing the rotation velocity of the rotation of the housing and apparatus for integrating and correlating the rotation angle with the determined first angle to determine said absolute rotation angle. 
     
     
       31. Tool apparatus according to claim 30, wherein said apparatus sensing the rotation velocity includes an optical gyroscope. 
     
     
       32. Tool apparatus according to claim 30, wherein said apparatus sensing the rotation velocity include a gyroscope. 
     
     
       33. Tool apparatus according to claim 32, wherein said gyroscope is an optical gyroscope. 
     
     
       34. Tool apparatus according to claim 32, wherein said gyroscope is a piezoelectric gyroscope. 
     
     
       35. Tool apparatus according to claim 14, wherein said second angle determining device includes apparatus sensing the angular acceleration of the housing and apparatus for doubly integrating and correlating the sensed rotation angle with the determined first angle to determine said absolute rotation angle. 
     
     
       36. Tool apparatus according to claim 14, comprising a rotation rate sensor assigned directly to the tool drive shaft.